The erythrocyte sedimentation rate is measured as part of the routine analyses performed on blood samples. This analysis can normally be performed using test tubes or cuvettes with a particular shape, suitable for optical reading by means of a transmitter-receiver that slides axially along the test tube. An example of a test tube suitable for this application is described in EP-B-898700. Appliances that use dedicated test tubes to measure erythrocyte sedimentation rate are described in WO-A-9743621 and in U.S. Pat. No. 5,133,208.
Appliances have also been developed that enable the erythrocyte sedimentation rate to be measured using not special test tubes, but the standard test tubes or cuvettes used for complete blood counts (CBC) or similar analyses on blood samples. Such appliances involve aspirating part of the blood sample contained in the cuvette or test tube for CBC into a capillary tube. The erythrocyte sedimentation rate is then measured inside the capillary tube. These appliances offer the advantage of enabling a single type of test tubes to be used for various routine analyses, including the erythrocyte sedimentation rate (ESR). They have considerable drawbacks, however, deriving from the fact that the blood sample must be drawn from the test tube by means of a pipette or capillary tube, which must subsequently be washed or replaced between one test and the next. This involves the production of liquid or solid waste that has to be disposed of, consequently increasing the complexity of the appliance and the corresponding cost of its management, as well as the production costs. Moreover, there is an inherent risk of contamination between the samples analyzed in series.